This invention relates to a tape printer, which comprises a printing head and a platen disposed such that they face each other, and in which an image source tape such as an ink ribbon and an image receiving tape are driven through a printing area between the printing head and platen for printing in the printing area an image on the image receiving tape from the printing head via the image source tape by, for instance, a thermal printing process or a thermal transfer process, the resultant image receiving tape being used as a label or the like.
Tape printers of the type noted are disclosed in European patent applications No. 0267890 and No. 0272232. In these disclosed tape printers, a thermal ink ribbon as an image source tape and a single-sided adhesive tape as an image receiving tape are accommodated in a tape cassette, which is loaded for use in a tape printer frame. A separable sheet is applied to the adhesive surface of the single-sided adhesive tape, the non-adhesive surface of which serves as a printing surface. In the frame, a thermal printing head and a platen are disposed such that they face each other and are movable relative to each other between an operative position, at which the head is urged against the platen, and an inoperative position, at which the former is spaced apart from the latter. When the tape cassette is loaded in the frame, the printing head is advanced into a head accommodation recess formed in the cassette, whereby the image source tape and image receiving tape are found in an overlapped state between the printing head and platen. When a printing operation is started, the thermal printing head is moved in the recess from the inoperative position to the operative position, and with both the tapes urged against the platen, an image is transferred from the head to the image receiving tape via the image source tape. The transferred image is a positive image when viewed from the side of the printing surface of the image receiving tape.
After the printing the image receiving tape is fed out from a tape outlet of the frame. At this time, it is cut by a cutter to a desired length, and the cut tape is used for usual display or as a label.
In the above prior art tape printer structure, however, the thermal printing head itself is movable between the operative and inoperative positions. Therefore, the tape cassette recess, into which the head is advanced, should have a large depth to sufficiently cover the range of movement of the head. This poses problems in the design of compact tape cassettes and layout of tape accommodation sections in the cassette housing The tape printer, in which the tape cassette is loaded, thus is inevitably increased in size.
The tape cassette recess should be made sufficiently large for the following reason as well. In the printing area, the image source tape such as an ink ribbon is found close to the printing head. Therefore, if there is looseness or sagging in the tape when the tape cassette is loaded, the tape is liable to be caught by the head and be broken or result in failure of tape running. In addition, it is necessary to load the tape cassette carefully, which is rather cumbersome. At any rate, the inoperative position of the printing head can not be set to be very close to the image source tape, and a certain minimum gap has to be provided with respect to the image source tape. The recess, therefore, is inevitably large.
As a further problem in the prior art tape printer, at the start of the printing operation the printing head is mechanically moved via a link mechanism to the operative position to urge it against the platen, which is stationary. That is, the operative position of the printing head is substantially fixed although the platen surface has a buffering action due to elasticity. Therefore, fluctuations of the accuracy of components directly influence the urging force of the head at the operative position and vary the printing pressure to disable uniform printing.